Catalyst has better Plack/PSGI integration than Mojolicious; in fact Mojolicious is often better deployed without Plack because the PSGI stuff just gets in the way of Mojolicious' home-brewed async stuff.

The whole point of Mojolicious is to be an integrated set of tools that work well together, whereas Catalyst is focused much more on being a part of the wider CPAN ecosystem, and generating its own ecosystem of extensions in turn.